The present invention relates to an improved terminal slowdown apparatus for an elevator.
In an elevator, the speed of a cage near the terminal floors is monitored and if an excessive speed is detected, it is necessary to safely land the cage.
As is well known, speed control of the cage is performed depending upon the speed pattern. The elevator has the structure for forming a terminal slowdown speed pattern which is different from the normal speed pattern, when the cage is near the terminal floors.
The terminal slowdown speed pattern is formed by contacting the cage with a landing floor selected in a machine room or a plurality of switches disposed near the terminal floors in a hoistway.
The relations are shown in FIGS. 1 and 2.
In FIG. 1, the reference .sub.ABC shows the normal speed pattern of the cage (not shown) in landing at the terminal floor (C) after being driven at a constant speed. The speed of the cage is normally controlled depending upon the normal speed pattern.
The reference .sub.DEC designates the lower floor landing speed pattern. If an error occurs in the normal speed pattern .sub.ABC to cause the pattern .sub.ABE , the speed pattern is switched to the terminal slowdown speed pattern to give .sub.ABEC .
The cage is controlled along the speed pattern .sub.ABEC whereby the speed of the cage is changed as shown by the broken line and the cage is safely stopped at the terminal floor (C).
However, when a deceleration is caused before reaching the specific speed, (hereinafter referring to as a short landing operation), the normal speed pattern is given by the reference .sub.ABC in FIG. 2.
If the error in the normal speed pattern occurs during an acceleration of the cage, the speed pattern is varied to the speed pattern .sub.A'B'E'C and the speed of the cage is changed so as to be shown by the broken line.
As it is clear from the drawings, the acceleration of the cage is significantly large in the negative direction and the sudden deceleration causes a shock to the passengers in the cage to provide an insecure feeling.